Some people might refer to this "voice" as their "gremlin." Censor, gremlin, doesn't matter. It seems like everyone has that voice (or sometimes, those voices) that tell them things that just are not true. It's important to be aware of that voice and to know when it is speaking so that we can acknowledge it and move on to do whatever it was we were going to do.
(I'm working with a group through Julia Cameron's book, The Artist's Way. I did this on my own many years ago and got out of the habit of doing some of the practices she introduces in the book. I am looking forward to picking them up again.)